July 31, 2015

Preliminary study looks at the impact of vitamin D on MS during pregnancy


Vitamin D, often called the sunshine vitamin, is produced by the body when a person’s skin is exposed to the ultraviolet B (UVB) radiation in sunlight. The vitamin can also be obtained be eating certain types of food, such as fatty fish or fortified foods like milk, or through supplementation. Many individuals do become vitamin D deficient, usually from a lack of UVB exposure (a problem during the winter months) coupled with a vitamin D deficient diet. Researchers have repeatedly linked this deficiency to an augmented risk of developing multiple sclerosis (MS), and some evidence points to an increase in disease severity in those already living with MS.

Lack of vitamin D is especially common among women between the ages of 15 and 40, and worsens further during pregnancy. As such, there is a need to evaluate the efficacy and safety of vitamin D supplementation as an MS therapeutic in pregnant women with low vitamin D status. To begin addressing this issue, a team of researchers from the Isfahan University of Medical Sciences in Iran conducted a very early, exploratory study to examine the effects of high dose vitamin D supplementation in pregnant women with MS. Their findings were published in the Iranian Journal of Neurology.

The Study

The study was open label, meaning both participants and researchers were aware of the treatment being given. Fifteen women between the ages of 20 to 40 were recruited to take part.  All participants had low vitamin D levels, were pregnant, and had MS.

The participants were randomly assigned to one of two treatment groups; the first, consisting of 6 women, received 50,000 IU’s – a very high-dose compared to the Health Canada Recommended Dietary Allowance (RDA) per day – of oral vitamin D once per week in addition to their routine care, while the second, consisting of 9 women, received their routine care only. Both therapeutic courses began at 12-16 weeks after the onset of pregnancy and lasted through to delivery.

Participants were evaluated every 8 weeks until time of birth, and then again 6 months later.  During evaluations, researchers measured the amount of 25(OH)D (a metabolite of vitamin D used as the standard indicator) in the participant’s blood, monitored for relapses, and assessed degree of disability (using the Expanded Disability Status Scale, EDSS).


The researchers acknowledged that this is an early pilot study with a very small participant size, and therefore cannot reliably determine the effect of high doses of vitamin D on MS relapse rate and disability during pregnancy. Instead, the goal was to gather preliminary data to inform larger, more rigorous studies in the future.

The overall relapse rate decreased in both women given vitamin D and those receiving routine care between pregnancy and 6 months after delivery; in fact, women receiving vitamin D supplementation experienced zero relapses within 6 months after delivery. However, vitamin D did not significantly impact the change in relapse rate between the two groups.

On the other hand, when assessed 6 months after giving birth, women given routine care were observed to have a slightly higher average disability score than women supplemented with vitamin D.

When measured at the 6-month follow-up, vitamin D levels were surprisingly not significantly higher for women that had received supplementation relative to those given only routine care.


This study suggests the possibility that high-dose vitamin D supplementation can influence MS-related disability, but not relapse frequency, when taken during pregnancy. Participants on the supplementation program also maintained elevated vitamin D levels up to six months after the final dose was given. These findings add to the growing body of evidence that supports vitamin D as potentially beneficial for the management of MS disability.  The study is also one of the first to test the efficacy of high-dose-vitamin D supplementation as an MS therapeutic for pregnant women, a period when vitamin D levels tend to naturally decline.

It is important to bear in mind that the study is preliminary and was meant to precipitate further research. The authors acknowledge that larger, more rigorous, double-blind trials are needed in order ensure the safety and efficacy of high-dose-vitamin D supplementation as an MS therapeutic during pregnancy. Replication and validation of the researchers’ initial findings are a critical next step before recommendations can be made to include high-dose-vitamin D supplementation as part of a routine care package for therapeutic treatment of MS in pregnant women. Trials to monitor for any possible long-term effects on mother and child are also required (general guidelines on vitamin D supplementation in pregnant women, including side effects associated with chronic excess vitamin D intake, are available on the World Health Organization website).


Etemadifar M et al. (2015).  Efficacy of high-dose vitamin D3 supplementation in vitamin D deficient pregnant women with multiple sclerosis: Preliminary findings of a randomized-controlled trial. Iranian Journal of Neurology. 14(2): 67-73.